John T Dungan Crockett County Tennessee

I'm looking for any information on the parents of John T Dungan (1866-1940). The first reference I can find for him is his marriage to Cora Patterson in Crockett County Tennessee 25 Sep 1892. He worked on the railroad and I think that is why the two census records for John T Dungan, one in Humboldt, Gibson, TN as head and another in Jackson, Madison, TN where he is listed as cousin in the home of James Dungan.

James is the son of Thomas Green Hill Dungan and Rebecca Clanton. This would make John's father William Abram Dungan, Isaac Andrew Allen Dungan, or James Dungan. These brothers were cousin to Isaac Hill Dungon through their father Thomas Mason Dungan's brother Nathan Dungan. It is worth noting that John T named one of his sons Isaac Hill Dungan which could indicate a family relationship (it is also possible that the younger Isaac Hill was named for a prominent business/political leader in Humboldt).

If anyone has any information that could help connect the dots or indicate that I'm reading too much into the data I've got thus far would be appreciated.